A conventional plate type heat exchanger generally consists of a plurality of heat exchanger plates, between which fluid streams with a different temperature are allowed to flow in a spatially separated manner. This enables the recovery of heat energy by means of the heat exchanged between the fluids.
From European patent document EP 1,842,616, a method for manufacturing a plate type heat exchanger is known. The resulting heat exchanger comprises a plurality of stacked heat exchanger plates formed from rectangular plate members. Each heat exchanger plate has flanges formed in the periphery of the plate. The flanges comprise flat portions on two opposing edges of the plate, which are bent towards one side of the plate, and bulge portions at the remaining opposing edges of the plate, which are bent toward the other side of the plate. Two heat exchanger plates are connected facing each other with one plate positioned upside down. In an alternating fashion, the flat portions or the bulge portions of adjacent plates constitute contacting surfaces. In this way, gap portions with openings are formed in between the plates, allowing for the fluids to exchange heat while flowing through these gap portions. It can be observed that for the combined heat exchanger plates in EP 1,842,616, a first gap portion or fluid channel is formed having first openings or fluid channel apertures with a hexagonal shape. A similar heat exchanger configuration with hexagonal fluid channel apertures is described in patent document US 2004/0080060.
The disadvantage of the known heat exchangers is that the corners of the irregularly shaped fluid channels of such a heat exchanger introduce undesired obstructions to the flowing fluid in the side corners of the fluid channels, representing a source of turbulence and an increased resistance to the flow. Furthermore, the corner geometry is complex, requiring additional sealing items, and is expensive to fabricate.